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Spare PgCert AI genearted cards > Epigenetics > Flashcards

Epigenetics Flashcards

1
Q

What is epigenetics?

A

Mechanisms enabling heritable transfer of gene expression profiles by adaptation of chromatin without influencing underlying DNA sequence.

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2
Q

What is chromatin?

A

The complex of DNA and proteins that forms chromosomes within the nucleus of eukaryotic cells.

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3
Q

What are the characteristics of euchromatin?

A

More dispersed, less heavily stained under EM, gene rich, transcriptionally active, more unique DNA sequences, often found in the center of the nucleus.

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4
Q

What are the characteristics of heterochromatin?

A

Condensed appearance, very densely stained under EM, gene poor, transcriptionally inactive, repetitive DNA sequences.

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5
Q

What are the two types of heterochromatin?

A

Constitutive: always condensed, near telomeres. Facultative: become repressed, can be activated.

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6
Q

What is a nucleosome?

A

The fundamental unit of chromatin.

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7
Q

What is the structure of a nucleosome?

A

Protein octamer containing H2A, H2B, H3, H4 x2; 2 wraps of DNA of 146 bp; H1 protein binds to linker DNA – another 20 bp.

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8
Q

What is the role of histone tails?

A

Basic amino acids at N terminal stick out from the core, serving as a primary level of regulation and allowing higher order organization.

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9
Q

What are histone modifications?

A

Chemical modifications to histone proteins that can affect gene expression.

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10
Q

What is histone acetylation?

A

The addition of acetyl groups to histones, which introduces a negative charge and loosens up the chromatin complex.

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11
Q

Who are the writers of histone acetylation?

A

Histone acetyl-transferases (HATs) use a cofactor Acetyl-CoA to introduce acetyl groups.

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12
Q

What is the role of histone deacetylases (HDACs)?

A

They remove acetyl groups, closing up chromatin and inactivating gene expression.

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13
Q

What are bromodomain proteins?

A

Readers that bind to acetylated histones and help recruit transcriptional machinery to promoters and enhancers.

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14
Q

What is the effect of histone methylation on gene expression?

A

It is context dependent, varying based on which residue is methylated and the degree of methylation.

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15
Q

What is the MLL chromatin complex?

A

A histone methyltransferase that can bind to H3K4 mono/di-methyl and then methylate it again.

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16
Q

What are Trithorax and Polycomb genes?

A

Genes important in development for expression of HOX genes, with Trithorax activating and Polycomb repressing gene expression.

17
Q

What are nucleosome remodellers?

A

Proteins that affect higher order interactions without chemically adding groups onto histone proteins.

18
Q

What is the function of SWI/SNF family nucleosome remodellers?

A

They contain bromodomain to bind acetylated histones and are associated with opening chromatin.

19
Q

What is the role of transcription co-activators?

A

They can have histone modifying activity, such as CBP, which is a coactivator and histone acetyltransferase.

20
Q

What is DNA methylation?

A

Modification of cytosine to 5-methylcytosine by DNA methyltransferase.

21
Q

What are CpG islands?

A

Regions of DNA with a high concentration of CpG sites, often unmethylated in constitutively expressed genes.

22
Q

What is the function of DNA methylation?

A

Prevents some transcription factors from binding to DNA, leading to long-term gene inactivation.

23
Q

What is genomic imprinting?

A

The expression of only one of the maternal or paternal alleles.

24
Q

What is the role of DNMT1?

A

Maintenance of methylation patterns after DNA replication.

25
Q

What is the effect of dysregulation of DNA methylation in cancer?

A

Methylation of tumor suppressor genes and hypo-methylation of oncogene regulatory regions can lead to cancer.

26
Q

What are epigenetic drugs?

A

Drugs that target epigenetic modifications, such as iDNMTs and iHDACs, to reactivate silenced tumor suppressor genes.

Spare PgCert AI genearted cards (6 decks)

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